Heat treatment and quenching of alloyed steels.



J. OHURGHWA RD. HEAT TREATMENT AND QUENGHING OF APPLICATION FILED SEPT.18;

ALLOYBD STEBLS.

Patented Sept. 29, 1908.

gating or retardation are.

JAMES GHUROHWARD, OF NEW YORK, N. Y.

HEAT TREATMENT AND QUENCHTNG 0F ALLOYED STEELS.

I Speeificationof Letters Patent.

' Patented Sept. 29, 1908.

Application filed September 18, 1907. Serial No. 393,489.

uct is rendered of-extr'aordinary toug ness and hardness.

Each successive heat or heat-wave is carried to a point a little beloweither the segrepoints of the corresponding alloying metal, the massbeing cooled or quenched after each successive heat or heat-wave.

For affording a better understanding to those versed in the art, I haveshown in the accompanying drawing a diagram illustrating the differentphases of the metal under a rising temperature.

In this drawing A is a period of restoration I where the alloying metalrenters the mass particle.

B is the retardation point. At this oint the alloying metal has beencomplete y restored and enters in a period of rest or retarded activity.

HC is the period. of rest or inactivity of the a oy.

D is the segregating point. 'Here a reversechemical action takes placeand the mass particle again siveats or throws out from itself thealloying metal.

E is the period of segregations, which commences at the segregatingpoint and continues on to the melting point. a

If the temperature is carried to within 100 F. of the retardation ointof the alloying metal and'tlie' mass 0 metal allowed to soak for a whileat this temperature, toration will be accomplished but not in so perfecta manner as if the temperature were carried to a point nearer theretardation point. It is very dangerous to attempt to carry arestoration temperature beyond the retardation point and into the zoneof rest or inactivity. This period oftime is so short, that it is morethan likely'that such treatthe res mentwould be extended beyond thesegregating point and then the restoration would only be partial.

All quenchings given above the retarda tron point of manganese shouldbewith a view of toughening only, and oils are thebest substances forthis use. brought into a proper or fit state for hardening until thetemperature is stopped at the retardation point of the manganesecontained in the steels. This point is generally known as therecalescent point. There are two actions occurring wit iin the body ofthe metal at this point, namely z-a thermochemical action which forces aphysical actlon, whereby the manganese 18 caused. to

release its bond or grip on the mass particle, the mass particlethereupon assuming a new shape or form, and the carbon contained in theparticle working its way out to the surfaces of the particle, leavinglittle or no carbon in the center thereof. This brings the hardeningelement-carbon-to the surface, a position where it can receive the chilland shock from the bath, causing the particle to collapse, shrink insize and harden, and, as the mass is an aggregation of particles thishardening is conveyed to the whole mass. Further hardening can be doneby a lurality of quenchings, if they follow down rom the retardationoint of manganese. The car: bon will not e re-arranged in the particleby any subsequent temperature provided, such subsequent tem erature ortemperatures being all below the retardation point of the manganese, butif a subsequent temperature is carried beyond the retardation point ofthe manganese the particle will again re-form and go back into its oldshape, carrying the carbon in with it.

By quenching in any ordinary or suitable manner two operations areconducted under one heat, namely the restoration of the alloy ing metaland the toughening and hardening of the mass itself by the quenching.This very materially reduces the cost of productionfand is of greatvalue to manufacturers of alloyed steels. The degree of hardness of theproduct can also be governed. If allowed to atmospherically cool it willbe hard, but not nearly so hard as when quenched and yet harder than hencooled more slowly.

This invention is amodification of that described and claimed in myLetters Patent The metal is not a little below the retardation point ofthe al No. 855,756, dated June 4th, 1907. a For more detailed statementof steps and temperatures employed see this patent.

Having thus described my invention I claim I. The herein describedmethod'of heattreating and hardening alloyed steels, which consists insubjecting the mass of metal to a series of heats or heat Waves ofsuccessively decreasing maximum temperature, designed to affect thealloying metals in order of their res ective segregating points, thefirst heat or eat-Wave being carried to a temperature a little below thesegregating point of the alloying metal having the highest segregatingpoint, and each successive heat or heat-wave to a temperature a littlebelow the segrega ing point of the corresponding alloying metal andquenching the mass after each successive heat or heat-Wave.

2. The herein described method of heattreating and hardening alloyedsteels, which consists in subjecting the mass of metal to a series ofheats or heat-Waves of successively decreasing maximum tem erature,designed to affect the alloying meta s in order of their respectiveretardation points, the first heat or heat-Wave being carried to atemperature l l I l lojying metal having the highest retardation point,and each successive heat or a little below the-"retarto a temperaturedation point ofthe corresponding alloying metal and quenching the massafter each successive heat or heat-wave.

decreasing maximum temperature, designedto affect the alloying meta s inorder of their respective retardation points, the first heat orieat-wave being carried to a temperature within 100 F. of theretardation point of the alloying metal having'the highest retardationpoint, and each successive heat or heat- Wave to a temperature Within100 F. of the retardation point of the corresponding alloying metal, andquenching the mass successive heat or heat-Wave.

In Witness whereof I have hereunto signed my name this 17th day ofSeptember 1907, in

the presence of two subscribing witnesses.

JAMES CHURCHWARD.

Witnesses: J. DPOAPLINGER, F. W. WIMAN.

heat-Wave

